Boom-hoist safety means



p 1930. E. H. LIGHTENBERG 1,775,435

BOOM HOIS'I' SAFETY MEANS Filed March 17. 1927 61/ 47 hing L Zjwownioz Patented Sept. 9, 1930 UNITED STATES PATENT OFFICE EBIGH H. LICHTENBEBG, OF MILWAUKEE, WISCONSIN, ASSIGNOB TO KOEHRING COK- PANY, OF MILWAUKEE, WISCONSIN, A CORPORATION BOOM-H0181 SAFETY MEANS Application filed March 17, 1927. Serial No. 176,087.

This invention relates to improvements in cranes of the boom hoist type and has for its primary object the prevention of overload on the beam and also prevention of backswinging when peaked up.

With these and other objects in View, as will in part hereinafter become apparent and in part be stated, the invention comprls'es an automatic control for efi'ecting cessation of movement of the parts either from overload or from movement beyond the plane of safety.

The invention in greater detail includes means for automatically discontinuing delivery of power under any such unfavorable conditions. I v

The invention also comprises certain other novel constructions, combinations and arrangements of parts as will be subsequently specified and claimed.

In the accompanying drawings,

Fig. 1 is a view in side elevatlon of a crane equipped with an illustrative embodiment of the present invention, the boom being seen in operative position in full lines and peaked up in dotted lines.

Fig. 2 is a fragmentary scale of thedead end anc cable.

Fig. 3 is a longitudinal, vertical sectlon taken approximately on the planes indicated by line 33 of Fig. 2, looking in the direction indicated by the arrows, parts being seen 1n elevation.

Fig. 4 is a transverse, vertical section taken on plane indicated by line 44 of Flg. 2, looking in the direction ind1cated by the arrows.

Figure 5 is an enlarged plan view, showing the spring contact constructic in detail.

In crane construction, it is common practice to mount the crane carbody as far at one side of the axis of its support as practicable, so that its weight and the weight of its contained machinery may serve as a counterbalance for the boom and load sustained thereby. Care must be accordingly exercised to prevent toppling forward under an excessive load on the boom and to prevent toppling rearward by peaking the boom up too high, that is causing 1t to approach too plan on enlarged orage of the hoist nearly an upstanding position where its weight is liable to be added to the weight of the crane car body instead of balanced against 1t. It is an essential object of the present invention to overcome the dan er of either of these possible exi encies, an the invention is, of course, app icable to practically any type of crane and especially any type with the counter-balancing body mounting, one embodiment of the invention being illustratively disclosed in the accompanying drawing, in which 1 is the crane car body rotatively mounted on the multi-plane tractor 2 and arranged ofi' center with respect to its support. A hoist boom 3 is pivotally connected, as usual, to the crane body but at the opposite side of the center of support from the major portion of car body 1. Anchored to the top of car body 1, and extending to the outer end of boom 3, as usual, is the cable 4, carrying the clam shell or other scoop, bucket or load carrier 5.

lhe anchorage of the dead end of cable 4 is of special construction and seen in detail in Figs. 2, 3 and 4. This special construction includes a yoke 6, pivoted to an eye 6 by a through bolt 6", said eye 6' extending from an appropriate yoke 9, bolted or otherwise suitably connected to an appropriate part of the upper portion of crane body 1. The bight of yoke 6 is connected to or integrally carries a preferably elongated loop 7, interlinked in a similarly elongated loop 8,which lastnamed loop terminates in an inwardly flaring sleeve 10, in which the cable 4 is effectively anchored. A guide band 11 is formed integral- 1y with or appropriately connected to loop 7 and is arranged substantially transversely thereof to encircle and slide along the loop 8. A compression spring 12 is arranged within the loo s 7 and 8 and interposed between the opposing ends of said loops, so that when outward longitudinal stress is exerted on loop 8 it compresses spring 12 against the interlinked end of loop 7. The band 11 serves effectively to guide the loops in their relative movements and also to restrain against such lateral play of the loops with respect to each other as might enable dislocatlon of spring 12. Band 11 is also employed as a contact carrier, althoulgh any other part of the loop 7 might be uti mod for this pu ose.

A contact plate 13 is fixed to one si e of band 11 and insulated therefrom by an insulating sheet or block 14 and secured thereto by a bolt or other appropriate fastening means 15. Electrical conductor contacts 15,

16 and 17 are also preferably clamped by the saidlfi pressed un er s cient load to occaslon the requisite travel of the band 11 to effect this result, such travel occurring only under excessive load.

Hoist mechanism and a motor for driving the same, such as an ordinaryinternal combustion en 'ne, are, of course mounted within crane car ody land may be of any of the well-known types in use. The power source, whether an internal combustion engine or otherwise, depends for continuity of its 0' eration on current supplied throu h the lea 17 and 16,the lead 17, in the case 0 an internal combustion engine, extending from the magneto, spark coil or other source of current,

and the lead 16 extending to the timer or distributor of the engine. The magneto or other source of current is, of course, grounded on the frame of the machine. It follows therefore that whenever an over-balancing or other excess load is picked up by the clam shell or other load carrier 5, the resilient anchorage of the cable 4 will cause the cable to move longitudinall to an extent, causing the loop 8 to move relative to the loop 7 sufliciently for bringin the lug 18 into contact with the plate 13. Vhen th1s occurs the current sup- .plied through the lead 17 no longer follows the lead 16 alone, but is divided between the two leads 16 and 17, the major portion of the current taking the path of less resistance through the plate 13, lug 18, and connected parts to the ground connection of the magneto or other source of current. The motor is thereby short-circuited and delivery of power discontinued.

Extending from a point in contact with the, i plate 13, preferably by being interposed between the contact of leads 16 and 17 and plate 13, is an electrical conductor or lead 19 arran ed to extend along the cable 4, being prefera ly sustained in position along the cable by appropriate clips 20, 20, en a ing the cable 4 and enga ing, but insulate rom, the conductor of lea 19.

Well up the cable 4 and at such a height in the length of the cable as to effect the results desired at the required time to prevent a boom for supportin loads the boom 8 from being raised too near a vertical tion that is from being picked up too high, the lead 19 is provided with a loose end ortion 21, having an exposed contaotor end ocated to contact with the boom 3, when the boom is sufiiciently elevated, as seen in dotted lines of Fig. 1. Hence, before the boom reaches a point of dangerous elevation, the boom will strike the exposed end of the pro ecting portion 21 of lead 20 and thereby close the circuit from the source of current through leads 17 and 19 to ground, and cessation 0 the operation of the motor will be thus Iegfgected to prevent further elevation of the It is to be noted that while the connections shown and described are especially well adapted for use in controlling the operation of an internal combustion engine, the shuntmg of the circuit incident to contact produced by excessive movement of one or the other parts involved, whereby a dangerous condition is avoided, is also well adapted for adaptation to motors of other types, so long as electric current is utilized as a controlling factor in the o ration of'such motors.

What is claimed is:

In combination, a crane com rising a body, roin the body and adapted to pea ed, an o crating cable "connected with the boom for e ecting elevation of the boom and load, said operating cable including a coupling, an electnc circuit contact device mounted on said coupling, the coupling comprising relatively movable parts shiftable incident to varying loads handled by the operating cable, the coupling device having a movable'part carrying a contact device cooperative with that previously mentioned, whereby to enable short circuiting of the circuit'including the first mentioned contact device, other contact means associated with the operating cableand contacting with the boom and connected with the first mentioned contact means whereby to short circuit the said electrical circuit substantially as described when the boom is peaked to a point beyond safety, and an electrical circuit common to said contacts.

In testimony whereof I afiix my sigature.

ERICH H. LICHTENB RG. 

